(a) Field of the Invention
The present invention relates to an organic light emitting diode (OLED) display and a method for manufacturing the same.
(b) Description of the Related Art
Recently, requirements for display devices, such as monitors and television sets, include devices that are thinner and lighter than in the past. In order to satisfy such requirements, liquid crystal displays (LCD) have replaced cathode ray tube (CRT) displays in many applications. However, an LCD requires an additional backlight for illumination because the LCD is a passive device. Also, the LCD has deficiencies in terms of response speed and viewing angle. For these reasons and others, displays incorporating an organic light emitting diode (OLED) have received increased attention.
An OLED display typically includes an emitting layer interposed between two electrodes, one for injecting electrons and the other for injecting holes to the emitting layer. The injected electrons and holes are coupled in the emitting layer, and excitons are thereby formed. The formed excitons emit light while losing energy. In this manner, the OLED display is a self-illuminating device that does not require an additional light source. Therefore, power consumption for an OLED display may be comparatively low. However, in order to further reduce the power consumption of the OLED display, the luminance efficiency thereof should be increased. Since the luminance efficiency is proportional to the number of excitons generated in the emitting layer, it requires electrons and holes to transfer in balance. Since hole mobility is generally greater than that of electrons, control of the hole mobility is required. In order to control the hole mobility, a hole blocking layer may be interposed between the emitting layer and a cathode. In this case, the current density of a driving voltage and the color stability thereof may be degraded because the mobility of electrons is also reduced with the hole mobility.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.